| | 8 | I spent most of the week working on the psphot analysis of very bright stars in stacks. I put together code to model these saturated stars with a simple radial profile, which I can then subtract. This seems to do a much better job than trying to get the PSF model to fit against the very wide wings of these bright stars. The magnitudes calculated from the radial profile model are reasonable for moderately saturated stars, but break down (as expected) for extremely saturated ones (eg, a 3rd magnitude star in a MD field comes in at 7th). With these radial profiles for the bright star model, we reduce or eliminate the clusters of false positives in halos around bright stars. There is a situation in the MD stacks which still causes some problems: if a faint object, which is still above the S/N cut for possible extended models, is close to a very bright star, the model fit can go very badly because it is influenced by the residual pixels of the very bright star. I am investigating options for more intelligent masking of the bright star cores to avoid these issues. |
